Effects of Fin Shapes and Arrangements on Heat Transfer for Impingement∕Effusion Cooling with Crossflow

Abstract

The present paper has investigated the effects of fins on the flow and heat∕mass transfer characteristics for the impingement∕effusion cooling with crossflow. The circular or rectangular fins are installed between two perforated plates, and the crossflow occurs between these two plates. The crossflow blowing ratio is varied from 0.5 to 1.5 for a fixed jet Reynolds number of 10,000. A naphthalene sublimation method is used to obtain local heat∕mass transfer coefficients on the effusion plate. A numerical calculation is also performed to investigate the flow characteristics. The flow and heat∕mass transfer characteristics are changed significantly due to the installation of fins. In the injection hole region, the wall jet spreads more widely than in the case without fins because the fins prevent the wall jet from being swept away by the crossflow. In the effusion hole region, a higher heat∕mass transfer coefficient is obtained due to the flow disturbance and acceleration by the fin. As the blowing ratio increases, the effect of fins against the crossflow becomes more significant and subsequently the higher average heat∕mass transfer coefficients are obtained. In particular, the cases with rectangular fins show an approximately 40–45% enhancement at the high blowing ratio of M=1.5. However, the increase in the blockage effect results in increased pressure loss in the channel.